This application, Novel serotonergic, pro-cognitive antipsychotic therapies, is in response to PA-08-142: Pharmacologic Agents and Drugs for Mental Disorders (SBIR [R43/R44]). Schizophrenia is a devastating brain disorder that affects approximately 0.7% of the global population. The symptoms of schizophrenia can be grouped into three major categories: positive (e.g. hallucinations and delusions), negative (e.g. social isolation and inappropriate emotional response), and cognitive symptoms. The cognitive symptoms of schizophrenia include impaired attention and disruption of working memory, an essential type of short term memory. These fundamental cognitive processes are critical for the performance of day-to-day activities, and their disruption in schizophrenia is a key factor underlying the inability of patients to integrate successfully into society. Indeed, the cognitive deficits associated with schizophrenia are recognized as a core component of the disorder. Currently available antipsychotic therapies are effective at ameliorating the positive symptoms of schizophrenia, but they are not effective at treating the negative or cognitive symptoms of the disease. Moreover, these therapies often cause significant side effects such as motor disturbances, weight gain, and diabetes. For these reasons, schizophrenia represents a major area of unmet medical need which must be addressed by the discovery and development of new antipsychotic therapies that are effective at treating the cognitive symptoms of schizophrenia with reduced potential for side effects. The overall goal of this proposal is to optimize a series of lead compounds we have identified with dual 5-HT2C receptor agonist and 5-HT6 receptor antagonist activities. Compounds with this novel pharmacological profile hold promise for yielding safe and effective treatments for the positive as well as the cognitive symptoms of schizophrenia. Such compounds are likely to have a significantly reduced risk for generating the undesirable side effects that are typically observed with currently available antipsychotic therapies. Successful completion of the specific aims outlined in this proposal will result in the identification of lead compounds with desirable pharmacological and drug-like properties. Furthermore, proof-of-concept for this novel target profile will be achieved by demonstrating antipsychotic and pro-cognitive efficacy in animal models with a selected lead compound. These achievements will provide a solid basis for a Phase II SBIR application to support further research aimed at selecting a clinical development candidate for the treatment of schizophrenia and its cognitive symptoms. A clinical development candidate with this novel profile would comprise a valuable asset within the pharmaceutical industry and would provide the basis of a successful commercial outcome for the research program. The research outlined in this proposal will directly benefit patients and their families and caregivers by leading to the discovery of safer and more effective medicines for the treatment of schizophrenia.